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    <title>ShellCheck: SC2020 – `tr` replaces sets of chars, not words (mentioned due to duplicates).</title>
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    <h1>SC2020 – ShellCheck Wiki</h1>
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    <h2
id="tr-replaces-sets-of-chars-not-words-mentioned-due-to-duplicates"><code>tr</code>
replaces sets of chars, not words (mentioned due to duplicates).</h2>
<h3 id="problematic-code">Problematic code:</h3>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC2020.html#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="bu">echo</span> <span class="st">&#39;hello world&#39;</span> <span class="kw">|</span> <span class="fu">tr</span> <span class="st">&#39;hello&#39;</span> <span class="st">&#39;goodbye&#39;</span></span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC2020.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">echo</span> <span class="st">&#39;hello world&#39;</span> <span class="kw">|</span> <span class="fu">sed</span> <span class="at">-e</span> <span class="st">&#39;s/hello/goodbye/g&#39;</span></span></code></pre></div>
<h3 id="rationale">Rationale:</h3>
<p><code>tr</code> is for <code>tr</code>ansliteration, turning some
characters into other characters. It doesn't match strings or words,
only individual characters.</p>
<p>In this case, it transliterates h-&gt;g, e-&gt;o, l-&gt;d, o-&gt;y,
resulting in the string "goddb wbrdd" instead of "goodbye world".</p>
<p>The solution is to use a tool that does string search and replace,
such as sed.</p>
<h3 id="exceptions">Exceptions</h3>
<p>None.</p>
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